Enhancing peroxymonosulfate activation through hemin impregnated bamboo biochar for oxidation of fluoroquinolone antibiotics

Antibiotics contamination in waterbodies poses a major threat to water ecosystem and public health. Eliminating these contaminants using an effective catalytic oxidation system remains a significant challenge. Herein, we report the fabrication of bamboo biochar-hemin (BBC@Hemin) composite as an effective peroxymonosulfate (PMS) catalyst for ciprofloxacin (CIP) degradation. The BBC@Hemin composite was synthesized via a simple one-step pyrolysis, demonstrating significant potential for the degradation of other antibiotics like norfloxacin and ofloxacin. Comprehensive physical characterization of the composite confirmed highly dispersed Fe and nitrogen on BBC. BBC@Hemin/PMS system showed 92.14% of CIP removal capability within 120 min (at pH = 5.85). The enhanced activity of the composite was ascribed to synergistic contribution of Fe and N-doped active sites. Nonetheless, ICP analysis revealed an extremely low Fe (0.42 wt%) loading in BBC@Hemin. Electron spin resonance (ESR) spectroscopy results confirmed the involvement of reactive oxygen species (ROS) in BBC@Hemin/PMS system. In addition, the system exhibits decent CIP removal performance in presence of anions (Cl⁻, SO₄²⁻, HCO₃⁻, H₂PO₄⁻), and humic acid (HA). Phytotoxicity results confirmed a notable improvement in the germination index for both rice and cucumber seeds after treatment, indicating less residual toxicity. Overall, this study demonstrates that the BBC@Hemin composite with minimal Fe content serves as a low-cost, eco-friendly, and robust catalyst for antibiotic degradation, contributing to the development of sustainable water purification technologies.